Shed conversion - which insulation to use?

[muggles]

I'm converting a garden shed into a shower block, and as part of this I want to insulate the interior walls between the stud frame, which is made of 3x2 timber. What is the best type of insulation to use for this? I was thinking something along the lines of a timber-frame specific PIR board insulation, something like Celotex TB3000 or Xtratherm Thin-R Timber Frame Board or Kingspan TW55 or K12

What thickness should I use (the walls are 3" thick)? Which product of the above, or any others you know of, are the best value (IE cheapest price for best insulation qualities)?

Any suggestions appreciated

 

[noseall]

a successful, mould free, shower block will need to be insulated fairly robustly in order to stave off the problems of condensation.

i would suggest full fill (75mm) celotex or kingspan between with a further 25mm insulation (integral vapour check) across the studs. foil tape all joints and mastic all perimeter abutments.
then use foil back boards to finish.

the floor and ceiling will need addressing too.

 

[muggles]

Ideal, cheers. Yeah I'd thought about the ceiling (the floor will have to stay as it comes) I have space for 4" insulation there if necessary (may well fill it up). It's not really practical to insulate over the top of the studs as well though due to size restrictions.

Moving on a bit from that, I'll need to cover the walls and ceiling in something once they're insulated. I was thinking plasterboard, which will subsequently be skimmed and painted. Would I need to use Moisturecheck on the ceilings or just the walls? Incidentally around the shower areas I'd tile rather than skim, I'm just thinking skim in the dry areas and on the ceiling.

Also, does anyone have any experience using Lafarge Aqua Board? Where do you get it from? Is there much difference in price between this and Moisturecheck?

 

[noseall]

i would use vapour check boards exclusively or at least use a vapour membrane.

aquapanel or aquaboard is about 3 times the cost of moisture resistant plasterboard.